h8.c

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/*
 * Copyright 2008-2011, IBM Corporation
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/io.h>

#include "wsp.h"

/*
 * The UART connection to the H8 is over ttyS1 which is just a 16550.
 * We assume that FW has it setup right and no one messes with it.
 */


static u8 __iomem *h8;

#define RBR 0       /* Receiver Buffer Register */
#define THR 0       /* Transmitter Holding Register */
#define LSR 5       /* Line Status Register */
#define LSR_DR 0x01 /* LSR value for Data-Ready */
#define LSR_THRE 0x20   /* LSR value for Transmitter-Holding-Register-Empty */
static void wsp_h8_putc(int c)
{
    u8 lsr;

    do {
        lsr = readb(h8 + LSR);
    } while ((lsr & LSR_THRE) != LSR_THRE);
    writeb(c, h8 + THR);
}

static int wsp_h8_getc(void)
{
    u8 lsr;

    do {
        lsr = readb(h8 + LSR);
    } while ((lsr & LSR_DR) != LSR_DR);

    return readb(h8 + RBR);
}

static void wsp_h8_puts(const char *s, int sz)
{
    int i;

    for (i = 0; i < sz; i++) {
        wsp_h8_putc(s[i]);

        /* no flow control so wait for echo */
        wsp_h8_getc();
    }
    wsp_h8_putc('\r');
    wsp_h8_putc('\n');
}

static void wsp_h8_terminal_cmd(const char *cmd, int sz)
{
    hard_irq_disable();
    wsp_h8_puts(cmd, sz);
    /* should never return, but just in case */
    for (;;)
        continue;
}


void wsp_h8_restart(char *cmd)
{
    static const char restart[] = "warm-reset";

    (void)cmd;
    wsp_h8_terminal_cmd(restart, sizeof(restart) - 1);
}

void wsp_h8_power_off(void)
{
    static const char off[] = "power-off";

    wsp_h8_terminal_cmd(off, sizeof(off) - 1);
}

static void __iomem *wsp_h8_getaddr(void)
{
    struct device_node *aliases;
    struct device_node *uart;
    struct property *path;
    void __iomem *va = NULL;

    /*
     * there is nothing in the devtree to tell us which is mapped
     * to the H8, but se know it is the second serial port.
     */

    aliases = of_find_node_by_path("/aliases");
    if (aliases == NULL)
        return NULL;

    path = of_find_property(aliases, "serial1", NULL);
    if (path == NULL)
        goto out;

    uart = of_find_node_by_path(path->value);
    if (uart == NULL)
        goto out;

    va = of_iomap(uart, 0);

    /* remove it so no one messes with it */
    of_detach_node(uart);
    of_node_put(uart);

out:
    of_node_put(aliases);

    return va;
}

void __init wsp_setup_h8(void)
{
    h8 = wsp_h8_getaddr();

    /* Devtree change? lets hard map it anyway */
    if (h8 == NULL) {
        pr_warn("UART to H8 could not be found");
        h8 = ioremap(0xffc0008000ULL, 0x100);
    }
}